150°f IAT on a stock 1.8
 

I recently installed ms3 pnppro, mtxl wideband, and the gm iat sensor on my 97 miata. Will turbo soon but right now, I took the advice.of several on here and laid the iat sensor in the stock airbox. With the car idling and up to operating temp, the iat temp on Tunerstudio gauge was saying it was 150 degrees. Isnt the crazy high for a stock 1.8? I hooked it up to the 3rd and 4th pins from the maf connector per the instructions.

It's possible. How long were you idling for and where did you place the sensor?
i know from personal experience if I sit in my miata idling in my garage tuning on my laptop, after 20 minutes or so my IAT will be pretty high. Like upper 130s. Don't know that i've ever gotten it to 150 but I suppose it is possible. Where is your intake drawing in its air?

i was in the garage tuning it with it idling for a while. Right now I have the sensor placed in the stock airbox until I install the turbo.

If a while to you is about 20 minutes or longer than I would say that stands to reason as normal. With the car stationary there is no inrush of air so the air the intake is taking in is the air that has been stagnant and getting hot in your engine bay.

Did you select the proper sensor under the Tools tab? They call it “calibrating”. It one usually selects from a pull-down menu.

DNM

Here's an easy test:

Idle the car for 20 minutes, open the hood, then rest your hand on the header heat shield. You must hold your hand for 60seconds for an accurate measurement.

good tip. Based upon the blisters now on my.hand I would say the temp is real ****ing hot